Formation of ethylene is apparently a general metabolic process in living organisms. However, the biogenesis and physiology of ethylene in animals is entirely unknown. Ethylene is a unique, simple unsaturated C2 hydrocarbon in that it is volatile gas, a naturally occuring plant hormone, a clinically useful anesthetic agent, and a common urban air pollutant. The profound physiological effects of ethylene in plants have been well documented. Ethylene has been detected in the exhaled breath of rats and humans. Production of ethylene was found in the subcellular fraction of rat liver and rat intestinal mucosa. It is of particular interest that in tumor bearing rats the maximum rate of ethylene production corresponded with the intensive growth of the neoplasm. Preliminary studies in our laboratory have shown that production of ethylene from methionine and methional were observed in mammalian tissue homogenates and tissue slice preparations. This phenomenon suggests that an enzyme or enzymatic system in mammalian tissues is actively involved in the synthesis of ethylene. The objective of this research project is to study the biogenesis of ethylene and its effects on the animal. This includes purification and characterization of the ethylene producing enzyme or enzyme system in mammalian tissue; to establish the metabolic pathway of ethylene synthesis in mammalian tissues; to explore and investigate effects of ethylene at the cellular as well as moleuclar level. Establishment of any substantial evidence of ethylene producing system and its effects in animal will open a new avenue to study the biochemistry of volatile hydrocarbon compounds and their relationship to animal physiology.